(1) Immediatelyat task onset, already with the irregular, random sequence, the group RT0/E+, consisting of the 13 participants who would latergain explicit knowledge of the repeating sequence without any specific speeding of RTs to this sequence, had larger P3 amplitudes than the other participants. (2) At task ending, all E+ participants,regardless of whether their responses were speeded by the repeating sequence, had larger P3 amplitudes than the E0 participantswho would not gain explicit knowledge. (3) Sensorimotor knowledgeof the sequence, indicated by delayed responses with random compared to regular sequences, was reflected by increasedfron to-central negativity around 300 ms with random compared to regular sequences.